/*
 * Copyright 2022 Expedia, Inc
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.expediagroup.graphql.generator.execution

/**
 * Wrapper used to represent optionally defined input arguments that allows us to distinguish between undefined value, explicit NULL value
 * and specified value.
 */
sealed class OptionalInput<out T> {

    /**
     * Represents missing/undefined value.
     */
    object Undefined : OptionalInput<Nothing>() {
        override fun toString() = "UNDEFINED"
    }

    /**
     * Wrapper holding explicitly specified value including NULL.
     */
    class Defined<out U>(val value: U?) : OptionalInput<U>() {
        override fun toString(): String = "Defined(value=$value)"
    }
}
